钛合金异质自冲铆接头力学性能及失效机理分析

Mechanical properties and failure mechanism analysis of titanium alloy heterogeneous medium self-piercing riveting joint

对钛合金异质单搭及T型自冲铆接头进行拉伸-剪切实验和剥离实验,对比接头的静力学性能,用扫描电子显微镜对接头典型断口进行研究,分析其微观失效机理。结果表明：TA1-Q215接头的最大失效载荷大于相同搭接类型的TA1-AA5052接头;TA1-AA5052单搭接头因下板断裂失效,为韧性断裂特征;TA1-Q215单搭接头上板铆钉孔撕裂处为韧窝形貌,铆钉与下板分离过程中,下板发生塑性变形并与铆钉产生严重刮擦现象;TA1-AA5052T型接头因铆钉与下板分离失效,下板出现明显的撕裂棱;当TA1-Q215T型接头失效形式为铆钉与上板分离时,上板撕裂处为准解理断裂机制;当铆钉与下板分离时下板撕裂处为韧性断裂,铆钉从下板剥离过程中产生刮痕。

Tensile-shear experiment and peel experiment of titanium alloy heterogeneous medium single-lap and T-type self-piercing riveting joints was carried out. Compared with its static performance of joint,typical fracture surface of joint was studied by scanning electron microscopy,and the microscopic failure mechanism was analyzed.Results show that the maximum failure load of TA1-Q215 joint is larger than that of TA1-AA5052 joint with the same lap type;the faliure of TA1-AA5052 single-lap joint is caused by lower plate fracture,which demonstrates ductile fracture feature.The apparance of rivet hole fracture surface of TA1-Q215 single-lap joint is dimple;during the separation process between rivet and lower plate,plastic deformation occurs on plate,and serious scratch phenomenon is also observed.The failure of TA1-AA5052 T-type joint is due to the separation of rivet and bottom plate,the bottom plate has obvious torn edges.When failure mode of TA1-Q215 T-type joint is the separation between rivet and upper plate,plate is torn due to quasi cleavage fracture mechanism.When rivet and the bottom plate separates,the torn bottom plate exhibites ductile fracture;during peeling process,rivet produces scratches on bottom plate.